well for the record jinbe does not use haki, But i am not saying that flamingo does not use haki. I'm talking about his power in general and more of the controlling part than the hurting part. from what we saw in his battle with croc we did not use haki on him. You could say he was just not trying. But why not control croc, controlling a logia in battle would be super useful. so why not unless he could not control them do to there fluid and moving bodies. All i mean is he might not be as effective against logias in that regard.